A prior art patent, U.S. Pat. No. 3,797,956, was issued to the inventors of the subject matter of the present application and said prior art patent utilized a draw bar in connection with the spindle for holding a tool holder in juxtaposition thereto and, consequently, each engagement of a tool holder with the driving spindle of the machine tool necessitated manual release of the draw bar to release the tool holder and subsequent tightening of the draw bar to connect another tool holder thereto.
Accordingly, it will be understood that the prior art patent disclosed a plurality of tool holders carried by a turret structure of a machine tool and each of the tool holders being juxtaposed in position for connection to the spindle of the machine, however, manual operation of the draw bar mechanism was required for each disconnection and subsequent connection relative to changing tool holders which carried different tools for successive machining operations.